This paper deals with pool boiling of water-Al2O3 and water-Cu nanofluids on porous coated, horizontal tubes. Commercially available stainless-steel tubes having 10mm outside diameter and 0.6mm wall thickness were used to fabricate a test heater. Aluminum porous coatings 0.15mm thick with porosity of about 40% were produced by plasma spraying. A smooth tube served as a reference tube. The experiments were conducted under different absolute operating pressures of 200 kPa, 100 kPa, and 10 kPa. Nanoparticles were tested at concentrations of 0.01%, 0.1%, and 1% by weight. In all cases tested, enhancement heat transfer was always observed during boiling of water-Al2O3 and water-Cu nanofluids on smooth tubes compared to boiling of distilled water. Contrary to smooth tubes, addition of even a small amount of nanoparticles resulted in deterioration of heat transfer during pool boiling of water-Al2O3 and water-Cu nanofluids on porous coated tubes in comparison with boiling of distilled water.